W211 E320 CDI - sense of humour failure impending (722.6 related)

[Evolution]

I've been scratching my head with this ridiculous car for a month now.

I bought it as spares or repair from a Merc specialist who allegedly didn't have time to sort it (ha).

It had the typical black death and buggered rad/ATF cooler.

Replaced rad, replaced cooler lines, replaced box and TC with a good working item from an S320 CDI.

Worked flawlessly for 5,000 miles, until one day I put my foot down to overtake a tractor, and it just acted like I'd dropped it into neutral. Couldn't select 1234, just PRND. P and N, could rev the engine all the way out, R and D, limited to 1,000rpm. If you turned it off and left it for a few mins, it would drive... but for roughly a minute before going "nah you're alright mate".

It had the same symptoms as conductor plate being faulty. Replaced it, worked fine for a few miles, then I got back underneath to reattach undertrays, etc and it was ****ing fluid from the newly fitted pilot bush. Turns out the new one was missing an O-ring. Deep joy.

Changed the whole valve body and conductor plate, drove it, lasted 15 miles before exactly the same symptoms came back. This time, I stripped out the entire gearbox, and found weird rusty deposits all over the divider plates in the clutch packs. I swapped the oil pump or just so it was refreshed (other one hadn't broken engagement tabs, etc), replaced the stator pack with a good working one (just loading up my massive parts cannon at this point), and rebuilt it all.

After all that, same symptoms, and there are no codes in the ECU for either gearbox, engine, or gear selector. It's the strangest thing because you will leave it alone, turn it on, and it'll work for a minute or two. Then it "fades" out. Reverse and drive takes ages to engage, and the amount of acceleration depletes in a linear fashion.

At the same time, a high pitched keening noise develops from what appears to be the transmission.

Wits End. Population: me.

Guess I'm looking at possibly a torque converter? I can only assume the rusty deposits I found in the sump went through the torque converter and blew out all the innards.

 

[LostKiwi]

You need to be very careful fitting the torque converter that you get it back in correctly. It's very easy to get wrong and if you do it breaks the oil pump.
That gives no drive...
Always fit the TC to the gearbox then bolt to the flex plate once it's all in.

 

[Evolution]

Yeah, I'm fully aware of that, I've been stripping and refitting auto boxes for a few years now. TC always goes on first, stand the trans on its arse, plop the TC in, and spin it until it engages.

It's had the same issues- that's why I stripped out the whole box and checked the pump. I've got 3 pumps, all good, all working.

 

[Uncle Benz]

Off the top of my head, the only thing that comes to mind is there are early and late transmission control modules, and pairing an early TCM with a late valve body and vice versa can have problems.

O ring on the filter is good?

 

[bembo449]

Interesting you went for the s320 gearbox and not another e320 box pal

 

[star]

Given you have rust on the internal plates, you have water ingress in the gearbox and it’s blocking the oil filter- so no drive after a few miles, getting lesser each time. Either the rad has failed or the s/h box had been contaminated before you fitted it. The high pitched whistle is the blocked filter. Seen it a few times before.

 

[mersum1es]

WHat are the fault codes?

 

[vincentfishing]

WHat are the fault codes?

He said no fault codes about 4 posts back !

 

[mersum1es]

He said no fault codes about 4 posts back !

Oh yeah, well hidden

Next question; what codes reader used? Deffo if in limp, restricting revs there should be triggering some code or event. AT least when fault is on, going read live data (especially now when OP knows soul of the transmission pretty well), should give some insight what going wrong.

 

[Evolution]

Off the top of my head, the only thing that comes to mind is there are early and late transmission control modules, and pairing an early TCM with a late valve body and vice versa can have problems.

O ring on the filter is good?

The car ran for thousands of miles with no issue on a 2002 valve body and 2005 TCM. It wouldn't surely just pack up one day?

Yep, it's had 3/4 different filters!

 

[Evolution]

Interesting you went for the s320 gearbox and not another e320 box pal

Same box, just different (bigger) torque converter.

 

[Evolution]

Given you have rust on the internal plates, you have water ingress in the gearbox and it’s blocking the oil filter- so no drive after a few miles, getting lesser each time. Either the rad has failed or the s/h box had been contaminated before you fitted it. The high pitched whistle is the blocked filter. Seen it a few times before.

There's no rust any more, it's had 3/4 fluid flushes since then. The filter has been replaced 3/4 times since the first issue. I took apart the 5,000 mile old filter and it wasn't awful, even with all the rust swimming in the sump.

I think the secondhand box was contaminated or had been sat around. The rad has been changed. All fluid that has been removed since has been perfect- no contam present.

Though, more worryingly, I dipped the trans a few times yesterday. Firstly, despite measuring how much I put in the first time around, the dipstick is showing as massively high... and I can see tiny, shiny metal flakes on the dipstick.

 

[Evolution]

Oh yeah, well hidden

Next question; what codes reader used? Deffo if in limp, restricting revs there should be triggering some code or event. AT least when fault is on, going read live data (especially now when OP knows soul of the transmission pretty well), should give some insight what going wrong.

Snap On Solus and an older VDO unit. I even checked all the live data with the Snap On unit. It's very comprehensive. Nothing appeared amiss. I'm absolutely baffled.

 

[matthew k]

I wonder if your better off just cutting your losses with this one and trying a new (secondhand) box. If there's been water/coolant inside yours it's surely toast? Alternatively, there seem to be quite a few organisations offering rebuild/reconditioning services for <£500 with a warranty on ebay etc.

 

[ajlsl600]

Oil way/pipe /valve getting obstructed?? Eng off, press drops, obstruction moves drops?
Shiny metal flakes, not good in new oil. And these modern trannies don't like anything in oil except oil.

 

[bob 6600]

Is the fluid level being checked at the correct temp? 80 degrees C I think.

 

[Evolution]

I wonder if your better off just cutting your losses with this one and trying a new (secondhand) box. If there's been water/coolant inside yours it's surely toast? Alternatively, there seem to be quite a few organisations offering rebuild/reconditioning services for <£500 with a warranty on ebay etc.

It hasn't had coolant through it. My suspicion is that it sat for a long time- possibly outside- and developed corrosion inside the box. The rust on the clutch pack divider plates is less than halfway round each disc, and the torque converter- which will usually be absolutely shagged by coolant ingress- has been flawless.

I cannot state this enough. It was flawless. I had no issues with it, at all, until one day... it just didn't work. 5,000 miles without a hitch. It's very odd.

I've got a few boxes sat around, I can probably build a really nice one myself. But as u I said, I've pulled the whole thing to bits and already replaced anything I've deemed a bit sub-par.

 

[Evolution]

Oil way/pipe /valve getting obstructed?? Eng off, press drops, obstruction moves drops?
Shiny metal flakes, not good in new oil. And these modern trannies don't like anything in oil except oil.

I did wonder this, but there's nothing that could possibly get in the way. I've stripped the whole box out, cleaned everything, put it back together, and I still have the same symptoms. The only thing really left is the torque converter...

Yes, I was ****ed off to discover the metal flakes. My least favourite cereal.

 

[Evolution]

Is the fluid level being checked at the correct temp? 80 degrees C I think.

My dipstick has measuring points for 25°C and 80°C. Even at 25°C- which is far lower down the stick- it's showing as being wildly overfull, despite getting exactly the right amount of fluid in it.

 

[ajlsl600]

Bizare, oil floats on water? Was the tc still full when you added the correct amount..